17
User Manual
Zenex Pro
Table 7.1
Parameter Description
Settings
Default Value
Not Applicable
(Default :
Not Applicable)
0.5 to 120.0 Seconds
(in steps of 0.5 secs.)
(Default : 0.5)
(Default : 10.0)
0.1 to 999.9
% OUTPUT POWER
This is a view only parameter that facilitates the indication of ‘%
Output Power’ computed by the controller PID algorithm. The
computed value lies between Min. power (0.0%) and Max. power
(100.0%).
CYCLE TIME
(For
‘PID’ Control)
For time-proportionating PID control, the output power is
implemented by adjusting the ratio of ON : OFF to a fixed time
interval, called ‘Cycle Time’. The larger the power the larger the
ON time and vice-a-versa.
Larger Cycle time ensures longer Relay/SSR life but may result in
poor control accuracy and vice-a-versa.
The recommended Cycle
Time values are; 20 sec. for Relay and 1 sec. for SSR.
PROPORTIONAL BAND
(For
‘PID’ Control)
The Proportional band is defined in terms of process value
deviation from the setpoint (also known as process error). Within
the band the output power is varied from maximum (100%) at
maximum deviation to minimum (0%) at minimum deviation. The
process value thus tends to stabilize at a point within the band
where the power input equal losses. Larger Band results in better
stability but larger deviation.
The Proportional Band value is automatically calculated by
controller’s Self-Tune feature and seldom requires any manual
adjustment.
INTEGRAL TIME
(For
‘PID’ Control)
The application of proportional band alone results in process
value stability within the band but away from the setpoint. This is
called steady state Offset Error. The integral action is incorporated
for automatic removal of offset error with minimum ocillations.
The Integral Time value is automatically calculated by controller’s
Self-Tune feature and seldom requires any manual adjustments.
0 to 1000 Seconds
(Default : 100)
PAGE 14 : PID CONTROL PARAMETERS
Section 7
